1. Field of the Invention
The present general inventive concept relates to an image forming apparatus, and more particularly, to an image forming apparatus to increase fluidity of a developer supplied to a developing chamber.
2. Description of the Related Art
In general, an electrophotographic image forming apparatus includes a laser printer, a photocopier, a multi-functional machine, etc., as an electronic apparatus forming an image on a printing medium through charge, exposure, development, transfer, and fusing processes.
As illustrated in FIG. 1 through 2B, a conventional image forming apparatus 1 includes a developing unit 20, a developer supplying unit 10 supplying a developer to a developing chamber J, and a transferring roller 30.
The developing unit 20 has a unit casing 21 forming the developing chamber J, and a plurality of rotating bodies 22, 23, 24, 25, and 26 accommodated in the unit casing 21.
The plurality of rotating bodies include a photosensitive body 24, a charging roller 22, a cleaning roller 23, a developing roller 25, and a supplying roller 26. The charging roller 22 charges a surface of the photosensitive body 24 to a predetermined electric potential, and the cleaning roller 23 cleans a residual developer on the charging roller 22.
The developing roller 25 develops the photosensitive body 24 with the developer that is supplied into the developing chamber J by the developer supplying unit 10. Also, the supplying roller 26 charges the developer provided to the developing chamber J by friction due to the same rotating direction with the developing roller 25, and supplies the charged developer to the developing roller 25.
The developer supplying unit 10 includes a developer supplying member 13 and an agitator 15. The developer supplying member 13 has a shape of a hollow pipe. The developer supplying member 13 receives the developer from a developer storing tank (refer to FIG. 4). The agitator 15 is disposed in the developer supplying member 13 and stirs the developer so as not to be cohered.
The developer supplying member 13 includes a developer outlet 14 which communicates with the developing chamber J and through which the developer is supplied to the developing chamber J. The developer outlet 14 may have a trapezoid shape as illustrated in FIG. 2A or a circular shape as illustrated in FIG. 2B.
There is no separate member in the developing chamber J, which moves the developer passed through the developer outlet 14 in a transverse direction to a feeding direction D of a printing medium P. Accordingly, the developer supplied to the developing chamber J through the developing outlet 14 is not evenly applied in the transverse direction to the feeding direction D. Thus, the image formed on the printing medium P varies in concentration along the transverse direction to the feeding direction D.
Particularly, an interval portion S between the developer outlets 14, where the developer is blocked from the developer supplying member 13, may be largely different in image concentration from a lengthwise portion L of the developer outlet 14 along the transverse direction to the feeding direction D.
The concentration difference can be confirmed with the naked eye by the printing medium P being entirely printed thereon with a yellow developer, and then a black developer is additionally provided to the developer storing tank. Then, the printing medium P printed thereon with the yellow developer is also printed thereon with the black developer. FIG. 3 is one portion of the photographed printing medium P printed thereon with the black developer.
As illustrated in FIG. 3, the image varies in concentration along the transverse direction to the feeding direction D. That is, referring to FIG. 3, the image concentration of an “A” portion corresponding to the developer outlet 14 is much higher than other regions not including the “A” portion.
The developer outlets 14 can be made as a single outlet along the lengthwise direction of the developer supplying member 13 without the interval portion S, so as to reduce the difference in the image concentration. However, this structure disadvantageously causes the developer supplying member 13 to be fragile.